1. Technical Field
The present invention relates to an electron emission device, and in particular, to an electron emission region and a method of manufacturing the same.
2. Description of the Related Art
Generally, the electron emission devices are classified into a first type where a hot cathode is used as an electron emission source, and a second type where a cold cathode is used as the electron emission source. The second type of electron emission devices include a field emitter array (FEA) type, a surface conduction emitter (SCE) type, a metal-insulator-metal (MIM) type, a metal-insulator-semiconductor (MIS) type, and a ballistic electron surface emitting (BSE) type.
The electron emission devices differentiate in their specific structure depending upon the types thereof, but basically have an electron emission unit placed within a vacuum vessel to emit electrons, and an image display unit facing the electron emission unit in the vacuum vessel to emit light or display the desired images.
With the FEA type electron emission device, electrons are emitted from electron emission regions due to the electric fields formed when driving voltages are applied to the driving electrodes placed around the electron emission regions. The FEA type electron emission device has a triode structure with cathode, gate and anode electrodes. The gate electrodes are first formed on a first substrate, and after an insulating layer is formed on the gate electrodes, cathode electrodes and electron emission regions are formed on the insulating layer.
With the above structure, there is no possibility that the gate and the cathode electrodes are short-circuited to each other during the processing thereof. As the electron emission regions are placed at the topmost area of the first substrate, a thick filming process, such as screen printing, can be easily applied thereto. The relatively simple processing steps related thereto are advantageous in making wide-screened display devices.
With the above-structured electron emission device, the electron emission regions are patterned by coating a photosensitive electron emission material onto the first substrate, and exposing it to light, followed by developing it. When ultraviolet rays are illuminate the electron emission material from the front side of the first substrate during the light-exposing step, the pattern of the electron emission regions is non-uniformly made, and the adhesion of the electron emission regions to the cathode electrodes is poor.
Accordingly, a backside exposure technique where the illumination of ultraviolet rays is made from the back side of the first substrate has been recently applied for the light exposing. However, a structure produced by such a method results in a high contact resistance between the electron emission regions and the cathode electrodes, a large voltage drop across the cathode electrodes and cracks in the insulation layer formed between the cathode and gate electrodes. All of these problems result in deteriorated image quality. What is needed is a design for a field emission device and a method of making that overcomes the above problems.